<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "The role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana"^^ . "Reductive assimilation of inorganic sulfate to sulfide is an essential metabolic process in higher plants for the synthesis of cysteine and all downstream compounds containing reduced sulfur in the cell. Sulfite reductase (SiR) palys a central role in the assimilatory sulfate reduction pathway by catalyzing the reduction of sulfite to sulfide. An Arabidopsis T-DNA insertion line (sir1-1) with an insertion in the promoter region of SiR was isolated in order to address the exact role of SiR in vivo. Detailed characterization of sir1-1 revealed that homozygous sir1-1 plants are viable, but severely affected in growth. Homozygous sir1-1 plants flower and set viable seeds, albeit later than wild-type plants grown under the same conditions. Evaluation of SiR transcript levels in the leaves of sir1-1 plants revealed that the mRNA was down-regulated to about 50% of wild-type level. Consequently, the amount of SiR protein and the SiR activity were reduced in the same manner. The significant differences between the leaves of sir1-1 and Col-0 plants for most of the sulfur-containing and other related compounds such as cysteine, O-acetylserine (OAS), sulfate, nitrate, total glucosinolates, total carbon (C), nitrogen (N), and sulfur (S) suggests strong perturbations in the entire metabolism of sir1-1 plants. A reduction of approximately 25.6-fold and 32.7-fold in the incorporation of 35S label into cysteine and GSH fractions, respectively, of sir1-1 leaves compared to wild-type plants was observed, suggesting the fact that the activity of SiR generates a severe bottleneck in the sulfur assimilation pathway. Investigations of the transcript levels through microarray analysis revealed that the expression of many genes related to sulfur metabolism was altered in response to reduced sulfide synthesis. Out of 920 selected genes related to sulfur metabolism, the expression of 67 genes in the leaves and 180 genes in the roots of sir1-1, were significantly up- or down-regulated compared to wild-type. The high affinity sulfate transporters, sulfate transporter 1;1 (SULTR 1;1) and sulfate transporter 1;2 (SULTR 1;2) showed a significant up-regulation in the roots of sir1-1 compared to Col-0. The up-regulation of the high affinity sulfate transporters in the roots of sir1-1 suggests that instead of steady-state sulfate levels, the amount of reduced sulfur present in the cell, likely forms the signal for their their induction. The preliminary results for a second T-DNA insertion line (sir1-2) strongly indicate that an insertion more closer to the gene, in the promoter region of SiR causes early seedling lethality. All results point towards the exclusiveness of SiR for sufite reduction and that its optimal activity is essential for the normal growth of Arabidopsis plants. Treatment of different Arabidopsis lines with selenate, which is quite similar to sulfate, caused an increase in the total sulfur and selenium contents of the plants. This might happen due to the up-regulation of sulfate transporters which might eventually lead to an increase in total sulfur and selenium due to elevated sulfate/selenate contents."^^ . "2008" . . . . . . . . "Muhammad Sayyar"^^ . "Khan"^^ . "Muhammad Sayyar Khan"^^ . . . . . . "The role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana (PDF)"^^ . . . "PhD_Thesis_Sayyar.pdf"^^ . . . "The role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "The role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "The role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana (Other)"^^ . . . . . . "preview.jpg"^^ . . . "The role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana (Other)"^^ . . . . . . "medium.jpg"^^ . . . "The role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #8863 \n\nThe role of sulfite reductase in assimilatory sulfate reduction in Arabidopsis thaliana\n\n" . "text/html" . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .